An optical receptacle is used as a part for optically connecting an optical fiber connector to an optical element such as a light receiving element, a light-emitting element, or the like in an optical module of an optical communication transceiver. For such an optical receptacle, a pigtail-type optical receptacle also is known in which the optical fiber is drawn out from a ferrule.
For example, in JP-A 2012-230275 (Kokai), a pigtail-type optical receptacle is proposed in which a ferrule that holds an optical fiber is held by a holder; and the holding force of the parts such as the ferrule, the holder, etc., is increased by press-fitting the holder into a case.
Also, in JP-A 2012-230275 (Kokai), because the rear end surface of the ferrule is positioned on the rear end side of the press-fit region of the case, the pressure that is applied to the rear end portion of the ferrule from the holder is reduced. Thereby, an undesirable concentration of an external force locally at one portion of the optical fiber at the rear end portion of the ferrule due to the inner diameter of the ferrule contracting due to the press-fitting can be suppressed. Also, the increase of the loss and the decrease of the strength of the optical fiber due to the concentration of the external force can be suppressed; and the reliability of the pigtail-type optical receptacle can be increased.
However, compared to a configuration in which the rear end of the ferrule is disposed in the press-fit region, it is necessary to set the ferrule and/or the holder to be long in the configuration in which the rear end surface of the ferrule is positioned on the rear end side of the press-fit region of the case. Therefore, for the pigtail-type optical receptacle, it has been difficult to downsize in the longitudinal direction of the receptacle main body portion (the portion frontward of the drawn out optical fiber) including the ferrule, the case, etc.
Generally, the configurations of optical transceivers are standardized; and the space of the electrical circuit including the optical elements and the like is undesirably encroached when the receptacle main body portion is lengthened. Also, higher speeds are necessary for optical transceivers as the IP traffic increases; and the space that is necessary for the electrical circuit is increasing due to the higher speeds of the modulation rate of the optical signals emitted from the optical elements, etc.
Therefore, for the pigtail-type optical receptacle, it is desirable to be able to downsize without causing a decrease of the reliability due to the concentration of the local external force in the optical fiber, etc.